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At present there is a particular interest in the relation between biodiversity, simply defined as the number of species present in the system, and function in the soil. This is part of a more general concern to conserve biodiversity and its role in maintaining a functional biosphere. The tacit assumptions in many current studies are that (i) by characterizing diversity one will be able to understand and manipulate the working of ecosystems and (ii) the ability of an ecosystem to withstand serious disturbances may depend in part on the diversity of the system. The importance of biodiversity in the functionality of ecosystems was stressed by Agenda 21, a document from the United Nations Conference on Environment and Development, prepared in Rio de Janeiro in 1992. The document promoted Scientific and international cooperation for a better understanding of the importance of biodiversity and its functions in ecosystems. There is now a growing body of experimental evidence that most organisms are functionally redundant and that the functional characteristics of component species are at least as important as the number of species per se for maintaining essential processes (Andren & Balandreau, 1999; Bardgett & Shine, 1999). We believe that at least some minimum number of species is essential for ecosystem functioning under steady conditions and that a large number of species is probably essential for maintaining stable processes in changing environments, the so-called ‘insurance hypothesis’ (Loreau et al., 2001). However, our theories on terrestrial ecosystems have been developed from above-ground observations, whereas comparatively few studies have been made in soil (Wardle & Giller, 1996; Ohtonen et al., 1997; Griffiths et al., 2000). The links between biodiversity and soil functioning are therefore poorly understood. Soil is fundamental and irreplaceable; it governs plant productivity of terrestrial ecosystems and it maintains biogeochemical cycles because microorganisms in the soil degrade,

Sooner or later, virtually all organic compounds including persistent xenobiotics and naturally occurring polyphenolic compounds. The living population inhabiting soil includes macro fauna, mesofauna, micro fauna and micro flora. In this brief review we focus on the relationship between microbial diversity and soil functionality, by considering that 80–90% of the processes in soil are reactions mediated by microbes (Coleman & Crossley, 1996; Nannipieri & Badalucco, 2003). Indeed, bacteria and fungi are highly versatile; they can carry out almost all known biological reactions. To provide a comprehensive view of the complex relations between microbial diversity and soil functionality we consider: 1 the complexity of soil as a biological system; 2 the problems in measuring microbial diversity and microbial functions in soil and the meaning of these measurements; 3 current ideas concerning the link between microbial diversity and soil functions; 4 instances when measurements of microbial diversity are unnecessary for a better understanding of soil functionality; and 5 the research needed for a better evaluation and manipulation of microbial diversity and soil functionality.

CHARACTERS-

BACTERIA- A wide variety of microbes occur in earth environment. Witch differs in characters, functions, and importance. Bacteria are the simplest and the most primitive organisms. They are cosmopolitan and are found in all the places wherever life is possible. Bacteria are considered to be the plant because they have rigid cell wall. They lack nuclear membrane and therefore, distinct nucleus and nucleoli are absent. Genetic material is represented by histone free DNA.

FUNGI- Fungi are widely distributed and are found wherever moisture is present. They are of great importance to humans in both beneficial and harmful ways. Fungi exist primarily as filamentous hyphae. A mass of hyphae is called a mycelium. Like some bacteria, fungi digest insoluble organic matter by secreting exoenzymes, then absorbing the solublized nutrients. Two reproductive structures occur in fungi asexual spores and sexual gametes.

VIRUS- In 1935 Stanley first separated virus by crystallization method. Since to till today many type of virus discover. Witch different in size and shape witch each other but re obligate parasite. Study of virus called “virology”. They express parasitic specificity. They contain genetic material DNA or RNA. They capable to replicate to genetic material. They also have antigenic characters. They replicate or produce only live cells. They sensitivity to chemicals, rays, stimulators, temperature etc.

These are most microbes but also other are actinomycetes, mycoplasma etc.

IMPORTANCE-

Some bacteria like E.coli have a major role or importance in biotechnological or microbiologic field. Because of its long history of laboratory culture and ease of manipulation, E.coli also play an important role modern biological engineering and industrial microbiology. The work of Stanely Norman Cohen and Herbert boyar in E.coli. Using plasmids and restriction enzymes to create recombinant DNA became a foundation of biotechnology. The useful physiological properties of yeast have lead to their use in the field of biotechnology, fermentation; of sugars by yeast is the oldest and largest application of this technology. Many types of yeasts are used for making many foods baker’s yeast in bread production, brewer’s yeast in beer fermentation.

Plant that have undergone transformation with Agro bacterium. The DNA transmission capabilities of Agro bacterium have been extensively exploited in biotechnology as a means of inserting foreign genes into plants. Marc Van Montagu and Jeff Schell discovered the gene transfer mechanism between Agrobacterum and plants. Witch resulted in the development of methods to alter Agrobcterium in to an efficient delivery system for gene engineering in plant.